Rocking chairs have been popular since the early 17th century. Besides the soothing rocking motion, rockers have been ideal for reading, knitting, sewing, and other seated tasks. From the beginning, rocking chairs have had problems which have driven inventors to make improvements. In fact, rockers were first known as “carpet cutters” because of the damage done to carpets by repeated rocking in the same place. Additionally, rockers were deemed too plain for the formal parlor, and so early chairs were consigned mostly to porches. Because of these and other problems, improvements to the rocking chair were almost immediately sought and innovations continue today.
One of the most recent innovations to the rocking chair concept is the glider chair. Glider chairs, similar to rocking chairs, provide a soothing repetitive rocking type motion, but unlike rocking chairs, they do not wear through carpet from repeated rocking in the same place. Typically, a glider chair consists of a base coupled to a seat in such a way as to allow the seat to swing forward and backward while the base remains stationary. Parallel arms pivotally connected to the base and seat are commonly used to achieve the desired swinging motion of the seat. Sometimes a glider chair will have an intermediate movable portion between the seat and the base so that when the chair is actively gliding the seat remains in a relatively horizontal position with respect to the base. In this case, parallel arms would extend between the intermediate movable portion and the base.
Because the glider chair seat moves freely, the force a person exerts on the seat when entering or exiting the chair easily moves the seat, causing an unstable support for a person attempting to rise from, or sit in, the glider chair. This motion makes it very difficult for elderly or disabled persons who rely on arm strength to enter or egress a chair to sit in traditional glider chairs. Additionally, it is difficult to move a glider chair because the glider portion will move some distance before actually moving the base of the chair.
To address this problem, locking mechanisms for glider chairs have been employed to lock the chair and prevent movement unless unlocked. These locks may be automatic so that when a person is in the chair, it is free to move, but automatically locks when the chair is unoccupied. Additionally, the lock may be a combination of an automatic lock and manual lock, such that the chair may be manually locked when the chair is occupied or unoccupied, but will also lock automatically when unoccupied if the manual lock is not engaged.
Typical automatic locking devices for glider chairs often have engagement problems. Some of these engagement problems are the result of multiple moving parts that are indirectly locked against the stationary base. Other engagement issues occur because the seats on glider chairs are easily mispositioned with respect to the locking device when the occupant leaves the chair, thereby causing lock engagement failures, and allowing the chair to slip suddenly and unexpectedly. External forces are applied to a chair can also cause lock engagement problems because the magnitude or direction of some external forces can overcome the securing forces of the locking device and allow the chair to slip out of the lock.